JP2019190077A - Steel beam and column-beam joint structure using steel beam - Google Patents

Abstract

To provide a steel beam which prevents occurence of welding cost, increase in the man hour, bending and warp of a beam web, and which can prevent local buckling by out-of-plane deformation of the beam web, and to provide a column-beam joint structure using the steel beam.SOLUTION: A steel beam 1 is mounted on a column 9, and has an H-shaped cross section. The steel beam 1 includes a vertical stiffener 11 disposed at a beam end part. Upper and lower end parts of the vertical stiffener 11 are joined with upper and lower beam flanges 3, 5, and the vertical stiffener 11 is not joined with the beam web 7 even though they are coming into contact with or approaching the beam web.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel beam and a column beam connection structure using the steel beam.

  In recent years, with the increase in size and space of buildings, the beam length tends to increase, and at the same time, the beam warp tends to increase in order to prevent deflection of the beam (increase the rigidity). Further, the thickness of the beam web having a small contribution to rigidity is preferably as thin as possible in order to reduce the amount of steel. As a result, an H-shaped beam having a large cross section and a thin beam web is used.

  In such an H-shaped cross-section beam having a large cross-section thin beam web, the width-thickness ratio of the beam web is increased, so that a local buckling phenomenon is likely to occur due to bending or shearing force generated during an earthquake. In particular, in the vicinity of the beam end close to the column where the bending moment increases, local buckling tends to proceed as compared with the center of the beam, and there is a problem that the required beam deformation performance cannot be obtained by local buckling.

In order to solve such a problem, as a method of preventing local buckling of the beam web at the beam end, for example, as proposed in Patent Document 1, a lateral stiffener perpendicular to the beam web 23 of the H-shaped cross-section beam 21 is used. 25 (see FIG. 6), a method of installing a plurality of vertical stiffeners 27 orthogonal to the beam web 23 proposed in Patent Document 2 (see FIG. 7), or Patent Document 3 There is a method in which the vertical stiffener 27 and the horizontal stiffener 25 are installed in combination (see FIG. 8).
In any of these methods, the stiffener is joined to the beam web by welding, and the purpose thereof is to control the width-thickness ratio or boundary condition of the beam web so that buckling is less likely to occur.

Japanese Unexamined Patent Publication No. 2016-23417 JP 2011-208434 A JP 2014-51822 A

However, in any of the conventional methods, all the stiffeners for stiffening the buckling of the beam web are welded to the beam web. There is also a problem in that it takes time to prevent bending and warping of the beam web due to the influence.
In addition, when a buckling stiffener such as a stiffener is joined to the beam web, part of the bending moment and shear force generated in the beam web is transmitted to the buckling stiffener, which can cause out-of-plane deformation of the beam web. There is also a problem that the buckling stiffener may be damaged by a force other than the accompanying out-of-plane force.

  The present invention has been made in order to solve such problems, and prevents an increase in welding cost and man-hours, bending and warping of the beam web, and local buckling due to out-of-plane deformation of the beam web. It is an object of the present invention to provide a steel beam that can be used, and a column beam connection structure using the steel beam.

(1) A steel beam according to the present invention is an H-shaped cross-section steel beam attached to a column,
It has a vertical stiffener disposed at the beam end, the upper and lower ends of the vertical stiffener are joined to the upper and lower beam flanges, and the vertical stiffener is in contact with or close to the beam web, but not joined It is characterized by this.

(2) Further, in the above (1), the upper and lower ends of the vertical stiffener are welded to the upper and lower beam flanges.

(3) Further, in the above (1) or (2), a buckling stiffener for stiffening the buckling of the vertical stiffener is provided, and the buckling stiffener is joined to the vertical stiffener. And is not bonded to the beam web.

(4) Further, in the above-described (3), the buckling stiffener is a lateral stiffener arranged in a direction intersecting with the longitudinal stiffener and in contact with or close to the beam web. It is characterized by.

(5) Further, in the above-described (3), the buckling stiffener is a face material arranged parallel to and in contact with or close to the beam web. It is a feature.

(6) Moreover, in the thing in any one of said (3) thru | or (5), it has two or more said vertical stiffeners, and the said buckling stiffener is provided so that it may span between the said adjacent vertical stiffeners. It is characterized by being.

(7) Further, in any of the above (1) to (6), the vertical stiffener closest to the beam end is arranged at a distance of 1/2 or less of the beam length from the beam end. It is characterized by being.

(8) Further, in any of the above-described (1) to (7), a plurality of the vertical stiffeners are provided, and an interval between adjacent vertical stiffeners is set to a distance of 1/2 or less of the length of the beam. It is characterized by being.

(9) A column beam connection structure according to the present invention is characterized in that the steel beam according to any one of (1) to (8) is bonded to a column.

The steel beam of the present invention has a vertical stiffener disposed at the beam end, the upper and lower ends of the vertical stiffener are joined to the upper and lower beam flanges, and the vertical stiffener contacts or is close to the beam web. However, since it is not joined, the out-of-plane deformation of the beam web can be suppressed.
In addition, since the vertical stiffener is not joined to the beam web, deformation caused by bending or shearing force generated in the beam web is not transmitted to the vertical stiffener, so that deformation such as torsion of the vertical stiffener can be prevented, and force caused by out-of-plane deformation of the beam web can be prevented. On the other hand, a stable buckling restraining effect can be exhibited.
Furthermore, the welding amount and man-hour of the beam web and the vertical stiffener can be reduced, and since the beam web and the vertical stiffener are not welded, the bending and warping of the beam web due to welding heat can be prevented. Man-hours and costs required for correcting warpage can also be reduced.

It is explanatory drawing of the steel beam of one embodiment of this invention, and is a side view (FIG.1 (a)) and arrow AA sectional drawing (FIG.1 (b)) of Fig.1 (a). It is a figure explaining the effect of the steel beam of one embodiment of the present invention. 3A is a cross-sectional view taken along the arrow in FIG. 2, FIG. 3A is a cross-sectional view taken along the line BB in FIG. 2A, and FIG. 3B is a cross-sectional view taken along the line CC in FIG. FIG. 3C is a cross-sectional view taken along the line DD in FIG. It is explanatory drawing of the steel beam of other embodiment of this invention, and is a side view (FIG.4 (a)) and arrow EE sectional drawing (FIG.4 (b)) of Fig.4 (a). It is explanatory drawing of the steel beam of other embodiment of this invention, and is a side view (Fig.5 (a)) and arrow FF sectional drawing (FIG.5 (b)) of Fig.5 (a). It is explanatory drawing of the steel beam of a prior art example, and is a side view (FIG. 6 (a)) and arrow GG sectional drawing (FIG.6 (b)) of FIG. 6 (a) (the 1). It is explanatory drawing of the steel beam of a prior art example, and is a side view (Fig.7 (a)) and arrow HH sectional drawing (FIG.7 (b)) of Fig.7 (a) (the 2). It is explanatory drawing of the steel beam of a prior art example, and is a side view (FIG. 8 (a)) and arrow II sectional drawing (FIG.8 (b)) of FIG. 8 (a) (the 3).

[Embodiment 1]
As shown in FIG. 1, a steel beam 1 according to an embodiment of the present invention has an H-shaped cross section including an upper beam flange 3, a lower beam flange 5, and a beam web 7 connecting them, and an end portion thereof The column 9 has a vertical stiffener 11 disposed between the beam upper flange 3 and the beam lower flange 5 so as to be orthogonal to the beam longitudinal direction at the beam end.
And the upper end part and lower end part of the vertical stiffener 11 are joined to the beam upper flange 3 and the beam lower flange 5, respectively, and the vertical stiffener 11 is in contact with or close to the beam web 7 but not joined. It is what.

The vertical stiffener 11 and the beam upper flange 3 and the beam lower flange 5 are generally joined by welding, but the present invention is not limited to this. For example, it is also possible to use bolt connection via an end plate.
Further, it is preferable that the vertical stiffener 11 and the beam upper flange 3 and the beam lower flange 5 are joined in advance at a factory.

  The vertical stiffener 11 is disposed in contact with or close to the beam web 7, but it is desirable that the clearance with the beam web 7 is small when the beam is disposed in proximity. Specifically, the thickness is preferably 3.0 mm or less in consideration of the manufacturing error of the beam, and more preferably 0.2 mm or less as the same range as the initial imperfection that has a small influence on the buckling resistance performance of the beam web.

The steel beam 1 generates bending moment and shearing force due to the upper loading load and horizontal load in the event of an earthquake. As the width-to-thickness ratio increases, the beam web 7 moves in the out-of-plane direction (in FIG. Deformation that protrudes in the orthogonal direction (left-right direction in FIG. 1B) is likely to occur.
In the steel beam 1 of the present embodiment, since the vertical stiffener 11 and the beam web 7 are not joined, the width-thickness ratio and boundary conditions of the beam web 7 do not change, and the load condition for causing out-of-plane deformation is the vertical stiffener 11. It is the same as a steel beam that you do not have.
However, in the present embodiment, since the vertical stiffener 11 is in contact with or close to the beam web 7, when the beam web 7 starts to be deformed out of the plane, the surface of the beam web 7 and the vertical stiffener 11 are brought into contact with each other. An external force is transmitted to the vertical stiffener 11 and resisting this can suppress out-of-plane deformation.
Therefore, the vertical stiffener 11 has sufficient thickness and height (bending rigidity) to restrain the out-of-plane deformation of the beam web 7.

Note that the vertical stiffener 11 closest to the beam end (column surface) is preferably disposed at a distance of 1/2 or less of the beam length from the beam end.
When a plurality of vertical stiffeners 11 are provided, it is preferable that the distance between adjacent vertical stiffeners is set to a distance of 1/2 or less of the beam.
The reason for this is as follows.
When a pure shear force acts on the beam web, buckling occurs in the 45 ° direction, and the greater the influence of the bending moment, the smaller the angle tends to approach the beam end. Therefore, in order for the vertical stiffener to effectively suppress out-of-plane buckling, it is desirable to place it at a position close to the center of buckling, and it is preferable to set it to 1/2 or less of the beam.

Next, the effect | action of the steel beam 1 of this Embodiment is demonstrated based on FIG.2 and FIG.3.
2 and 3 show an H-shaped cross-section beam 21 (FIGS. 2A and 3A) that is not buckled and a vertical stiffener 27 welded to the beam web 23. Stress transmission (in FIG. 2 (b), FIG. 3 (b)) and steel beam 1 (FIG. 2 (c), FIG. 3 (c)) of the first embodiment of the present invention An arrow) and out-of-plane deformation (gray ellipse in the figure) are schematically shown (FIG. 2), and deformation in a cross-sectional direction in each figure (FIG. 3).

As shown in FIGS. 2 (a) and 3 (a), the H-shaped cross-section beam 21 that is not buckled is subjected to large out-of-plane deformation in the direction of approximately 45 degrees in the case of a short beam that is predominantly sheared.
As the beam length increases, the bending moment becomes dominant, so the out-of-plane deformation is less than 45 degrees and tends to approach the vertical direction of the paper.

  On the other hand, as shown in FIG. 2B, in the case where the longitudinal stiffener 27 is welded to the beam web 23 and installed on the H-shaped cross-section beam 21, the beam web 23 is added to the upper and lower beam flanges, and the column 9 The vertical stiffener 27 or the adjacent vertical stiffener 27 is constrained in the vertical and horizontal directions and is divided into rectangular plates having a small width-thickness ratio in the beam material axis direction. As a result, out-of-plane deformation of the beam web 23 is suppressed, and the buckling occurrence region can be shifted from the longitudinal stiffener 27 near the beam flange where stress is high due to bending or from the column 9 to the center side of the beam. Can be increased.

On the other hand, since the longitudinal stiffener 27 and the beam web 23 are joined by welding, in-plane and out-of-plane stresses generated in the beam web 23 are transmitted to the longitudinal stiffener 27 (see FIGS. 2B and 3B). ).
As a result, a three-dimensional stress is generated in the longitudinal stiffener 27 in the strong axis and weak axis directions, and a torsion phenomenon occurs. Therefore, depending on the load condition, the restraining effect of the out-of-plane deformation of the beam web 23 may be reduced. is there.

On the other hand, in the steel beam 1 of the present embodiment, the longitudinal stiffener 11 is not joined to the beam web 7, so that the out-of-plane deformation of the beam web 7 is an H-shaped cross-section beam that is not buckled. Like 21, it tends to occur in an oblique direction (see FIG. 2C).
However, if the out-of-plane deformation is to occur, the out-of-plane deformation in the vicinity of the vertical stiffener 11 is constrained by the contact between the vertical stiffener 11 and the beam web 7, and as a result, the range divided by the vertical stiffener 11 having a small width-thickness ratio. It is possible to keep the deformation at (see FIG. 3C). In addition, since the vertical stiffener 11 and the beam web 7 are not welded to each other, stress due to shearing or bending generated in the beam web 7 is not transmitted to the vertical stiffener 11. For this reason, the vertical stiffener 11 is not twisted, and a stable shape can be maintained between the upper and lower beam flanges.

As described above, according to the steel beam 1 of the present embodiment, welding costs and man-hours are increased, the bending and warping of the beam web 7 are prevented, and local buckling due to out-of-plane deformation of the beam web 7 is prevented. can do.
Further, since deformation caused by bending or shearing force generated in the beam web 7 is not transmitted to the vertical stiffener 11, deformation such as torsion of the vertical stiffener 11 can be prevented, and stable buckling can be performed against the force due to out-of-plane deformation of the beam web 7. The restraint effect can be demonstrated.

[Embodiment 2]
The steel beam 13 according to the present embodiment will be described with reference to FIG. In FIG. 4, the same components as those in FIG. 1 showing the first embodiment are denoted by the same reference numerals.
The steel beam 13 according to the present embodiment is provided with a lateral stiffener 15 having a function of preventing out-of-plane deformation of the beam web 7 and a function as a buckling stiffener for stiffening the buckling of the vertical stiffener 11. It is.
The lateral stiffener 15 is disposed so as to be orthogonal to the vertical stiffener 11 and to be in contact with or close to the beam web 7. Further, the vertical stiffener 11 closest to the beam end is provided between the vertical stiffener 11 and the column 9, and when there is a vertical stiffener 11 next to the vertical stiffener 11, it is provided so as to extend over the adjacent vertical stiffener 11. Yes.
The lateral stiffener 15 is close to the beam web 7 but is not welded to the beam web 7 and is joined only to the vertical stiffener 11 or the column 9 by welding.
The clearance between the lateral stiffener 15 and the beam web 7 when the lateral stiffener 15 is brought close to the beam web 7 is preferably the same as the clearance between the vertical stiffener 11 and the beam web 7 described above.

  Here, assuming a beam with a dominant shearing force, the out-of-plane deformation of the beam web 7 will occur in an oblique direction of about 45 degrees, so the lateral stiffener 15 is placed at a position where the out-of-plane deformation seems to be dominant. ing. As a result, even when out-of-plane deformation that cannot be suppressed only by the vertical stiffener 11 occurs, it is possible to suppress the same out-of-plane deformation by the lateral stiffener 15, and the out-of-plane restraining force is further increased.

Furthermore, when the beam is large, the vertical stiffener 11 may be elongated, and the vertical stiffener 11 itself may be buckled in the out-of-plane (weak axis) direction due to the axial stress from the beam flange. By installing the horizontal stiffener 15, it also has a function as a stiffener for preventing the vertical stiffener 11 from buckling.
If a lattice-like stiffener group composed of the vertical stiffener 11 and the horizontal stiffener 15 is manufactured in advance and the stiffener group is installed on the beam flange 3 or the column 9, the vertical stiffener interval can be easily adjusted. The effect is obtained.

The above embodiment is an example. For example, the number and arrangement of the vertical stiffeners 11 and the horizontal stiffeners 15, the plate thickness, and the like may be appropriately changed depending on the load condition.
In the above example, the horizontal stiffener 15 is provided so as to be orthogonal to the vertical stiffener 11. However, the horizontal stiffener 15 is not necessarily orthogonal to the vertical stiffener 11, and is disposed so as to intersect with the vertical stiffener 11. In addition, depending on the buckling shape of the beam web 7, the beam web 7 may be arranged in the direction of approximately 45 degrees with respect to the longitudinal stiffener.
Even if the lateral stiffener 15 is not brought close to the beam web 7, that is, even if it is arranged at a certain distance from the beam web 7, it functions as a buckling stiffener for the vertical stiffener 11. Good.

[Embodiment 3]
The steel beam 17 according to the present embodiment will be described with reference to FIG. In FIG. 5, the same parts as those in FIG. 1 showing the first embodiment are denoted by the same reference numerals.
The steel beam 17 according to the present embodiment is configured such that a face member 19 is provided so as to extend over the adjacent vertical stiffeners 11 in place of the lateral stiffener 15 according to the second embodiment. The face material 19 is in contact with or close to the beam web 7 as in the case of the lateral stiffener 15, but is not welded to the beam web 7.
It is desirable that the face material 19 is disposed on the side closest to the beam web 7 in the vertical stiffener 11 to reduce the clearance between the beam web 7 and the beam web 7.
Compared with the lateral stiffener 15, the face material 19 can suppress the deformation of the beam web 7 out of the plane with the surface instead of the line, and thus the out-of-plane deformation restraining effect is further enhanced.

In addition, said embodiment is an example and the face material 19 used for a buckling stiffener may be a member integrated with a longitudinal rib using grooved steel etc., and is not restricted to a rectangle. The beam web 7 may have a shape corresponding to the out-of-plane deformation region.
Similarly to the second embodiment, the clearance between the face material 19 and the beam web 7 when the face material 19 is brought close to the beam web 7 is approximately the same as the clearance between the vertical stiffener 11 and the beam web 7 described above. It is desirable to do.
However, even if the face material 19 is arranged without being brought close to the beam web 7, it functions as a buckling stiffener for the vertical stiffener 11, so such a mode may be used.

1 Steel beam (Embodiment 1)
3 Beam upper flange 5 Beam lower flange 7 Beam web 9 Column 11 Vertical stiffener 13 Steel beam (Embodiment 2)
15 Horizontal stiffener 17 Steel beam (Embodiment 3)
19 Face material <Conventional example>
21 H-shaped cross section beam 23 Beam web 25 Horizontal stiffener 27 Vertical stiffener

Claims (9)

A steel beam with an H-shaped cross section attached to a pillar,
It has a vertical stiffener disposed at the beam end, the upper and lower ends of the vertical stiffener are joined to the upper and lower beam flanges, and the vertical stiffener is in contact with or close to the beam web, but not joined A steel beam characterized by that.   The steel beam according to claim 1, wherein upper and lower ends of the vertical stiffener are welded to the upper and lower beam flanges.   2. A buckling stiffener for stiffening the buckling of the longitudinal stiffener, the buckling stiffener being joined to the longitudinal stiffener and not joined to the beam web. Or the steel beam of 2.   The steel beam according to claim 3, wherein the buckling stiffener is a transverse stiffener arranged in a direction intersecting with the longitudinal stiffener and in contact with or close to the beam web.   The steel beam according to claim 3, wherein the buckling stiffener is a face member disposed parallel to and in contact with or close to the beam web.   The steel beam according to any one of claims 3 to 5, wherein a plurality of the vertical stiffeners are provided, and the buckling stiffener is provided so as to extend between the adjacent vertical stiffeners.   The steel beam according to any one of claims 1 to 6, wherein the vertical stiffener closest to the beam end is disposed at a distance of ½ or less of the beam from the beam end.   The steel frame according to any one of claims 1 to 7, wherein a plurality of the vertical stiffeners are provided, and an interval between adjacent vertical stiffeners is set to a distance equal to or less than ½ of a beam. Beams.   A beam-to-column connection structure, wherein the steel beam according to any one of claims 1 to 8 is bonded to a column.